Field of the Invention
This invention relates to line brattices in mines and more particularly to an extensible line brattice.
In underground mining operations, and in particular in the mining of coal in deep mines, control of ventilation is of critical importance. It is known that proper ventillation is necessary especially in those mines which are subject to gaseous conditions. Proper ventilation consists of moving large quantities of fresh air in the proper direction through the mine passageways.
In many instances the direction of the flow of fresh air is controlled by fixed walls called "mine stoppings." These permanent installations direct the air within the mine passageways throughout most of the mine.
At times temporary installations called "line brattices" are used prior to or in place of the installation of the permanent mine stoppings to control the flow of fresh air in areas where active mining is still going on. Such "line brattices" are conventional and usually comprise a frame made of mine timbers erected at spaced distances and a brattice cloth attached to the mine timbers to form a curtain which directs the flow of air in the mine. The brattice cloth may be jute, canvas or scrim-reinforced plastic material. "Line brattices" normally extend from a fixed end connected to a wall in the mine to a free end around which air can flow.
For safety reasons the roof areas of mines are supported by roof bolts. Roof bolts are long metal rods secured in the roof of the mine and support plates having substantial surface areas to keep the roof of the mine from collapsing.
At times the mine workers may be required to install line brattices in areas that have not yet been supported by the roof bolt and plate installations. At other times, mine workers may have to cross areas where roof bolts and plates have not been installed.
To provide for the safety of mine workers, it has been found advantageous to provide an extensible line brattice so that the flow of fresh air can be controlled in areas unprotected by roof bolts and plates. An extensible line brattice is connected to the free end of the line brattice.
It is important that there be proper ventilation at the working face of the mine and this can be accomplished by moving an extensible line brattice into place as the mining operation continues.
Various types of extensible line brattices have been suggested but have been rejected because they were impractical. Extensible line brattices which have not been practical have included those with tracks placed in or on the ground level of the mine passageway. Because of dirt and lumps of mined material, these tracks become clogged and useless.